Electric switch



De- 19, 1933. F. H. osBoRNE ELECTRIC SWITCH Filed oct; s1. l195o ww, m,E L J NIMF ,L www.. l. E

lNvENT'oR F 50 BY ATTO l?, 1933. F H, OSBORNE 1,940,267

ELECTRIC SWITCH Filed OCtA. 51. 19.30 2 Sheets-Sheet 2 lNvENToR msi/:mf

ATTO EY Patented Dec. 19, 1933 ELECTRIC SWITCH Fred H. Osborne, Chicago,Ill., assignor, by

mesne assignments, to Grigsby-Grunow Company, a corporation o! IllinoisApplication October 31,

12 Claims.

This invention relates to electric switches, and particularly to athermostatic switch for use in connection with refrigeration systems. Inorder to automatically control-refrigerator mechanism, it is customaryto provide a volatile substance such as liquid sulphur dioxide in acartridge disposed in heat conducting relation to the portion of therefrigerating system whose temperature is to be controlled. Thiscartridge is in communication with a chamber having an expansible wall,usually of the bellows type and known as a sylphon bellows. Suitableswitching mechanism is disposed in co-operative relationship to saidbellows so that as variations in temperature occur, variations inpressure within the bellows result in movement of the switchingmechanism.

As is well known, the thermostatic switches must have a denitetemperature range in which `to operate, in order to result in theopening and closing of the switch. It is customary to associate toggleor spring biased mechanism with the switch so that the switch will besnapped from one position to another. Such mechanism usually has extremepositions of stable equilibrium with intermediate positions of unstableequilibrium. Where the temperature range within which the mechanismoperates is great, the snapping positions are. sufficiently separated onthe opposite sides of the neutral axis of the mechanism so that stableoperation of the mechanism is obtained. However, as with refrigerators,the temperature range within which the device must operate is small.'Ihis results in changing the character of the stable positions ofequilibrium into more or less unstable positions and at times may causechattering at the contacts, with consequent arcing. Such action isprimarily due to. the fact that the mechanism between the switchcontacts and the sylphon bellows only has, as a rule, one neutral axisacross which some portion of the mechanism must travel to go from onestable position to the other stable position.

An object of this l invention is to devise a switch mechanism in whichthe switching member will be positively snapped under all conditions.

An additional object is to devisea switch mechanism in which theswitching member will be positively snapped from one position to anotheras soon as the primary actuating member is moved a predetermineddistance irrespective of howsmall this, distance may be set.

Additional objects are to devise a switch which 1930. serial No. 492,425

(ci. zoo-14o) will not chatter, which will be simple in construction andcheap to manufacture.

In the drawings,

Figure 1 is a side elevation of the switch with its volatile liquidcartridge;

Figure 2 is a top view looking down upon the switch of Figure 1 with thecartridge omitted;

Figure 3 is a view showing the disposition of the cartridge adjacent theevaporator;

Figure 4 is a viewrof the pivoted members showing their relation to eachother; and

Figures 5 and 6 are details.

The switch proper comprises a housing 1 provided with side anges 2 and 3for mounting. Housing 1 consists of side walls 5 and 6 joined by endwalls 'l and 8. Wall 7 is provided with an upwardly extending slot intowhich is disposed a sylphon bellows 10. Inasmuch as the construction ofsuch bellows is old and wellknown, further description thereof is deemedunnecessary. Bellows is provided with a coupling end 11 and is rmlymaintained at wall 'l by means of nuts 12 and 13 on opposite sides ofwall 7. y

The coupling end of sylphon bellows 10 has joined thereto a flexiblepipe 15 communicating with a metal cartridge 16 containing` a quantityof liquid sulphur dioxide.

The free end of sylphon bellows 10 is enclosed by a cap 20 provided witha pair of diametrically disposed pivots 21. Pivotally mounted in walls 5and 6 of the housing by lmeans of bolts 23 and 24 is a U-shaped memberhaving arms 25 and 26 and an intermediate section 27. It will be notedthat arms 25 and 26 engage pivot bolts 23 at the ends of said arms andalso engage pivots 21 at intermediate portions of said arms. Thedistance along arms 25 and 26 between pivots 21 and 23 is preferablysmall so that a small motion of cap 20, induced by the expansion andcontraction of bellows 10, will suffice to move intermediate portion 27through a substantial distance.

Side walls 5 and 6 of the housing are preferably provided withextensions 30 at the top thereof, through which project another pair ofpivot bolts 31 and 32. In order to clear these bolts, arms 25 and 26 ofthe U-shaped member are provided with elongated slots 35. Pivotallymountedbetween bolts 31 and 32 is a generally U-shaped member 36 havinga cross-piece 37 provided at each end thereof with arms 38. Each of arms38 consists of two right angle portions 39 and 40 with the pivot bolts31 and 32 going through portion 41 of said member. Cross piece 37 isprovided with a tongue 43, while connecting portion 27 is provided witha similar tongue 44. Between these two tongues, there is disposed a coilspring tending to pully portions 27 and 37 together. It will thus beseen that pivoted member 36 has two endpositions of. stable equivmaintain said contact rigidly in position. A

current lead 64 connects contact 60 with the terminal 65, while anotherterminal 66 carries a .stationary contact 67 adapted to co-op'erate withmovable contact 60. The terminals and station-ary contacts are suitablymounted on housing 1 by means of insulating strips 70 and 71.

Arms 40 of pivotal member 36 are each provided with a channel 75 inwhich extensions 53 and 54 play. It will be noted that the width of thechannel 75 is slightly greater than the width of extensions 53 and 54;hence, sufficient motion of member 36 on pivots 31 and 32 will cause thecontact bearing member to be engaged by the sides of channels 75 and bemoved. In order to impart snap'motion to the contact bearing member,crosss portion 52 is provided with a suitable aperture 76 into whichprojects one end of a spring 77. Another spring 78, rigidly mounted onend wall 8 tends to buckle spring 77 and results in a toggle actionbetween spring 77 and the contact bearing member. In order to limit thetravel of movable contact 60, a

\ phon bellows.

bolt 80 with a stop nut 81 is provided and is adapted to engage inwardlycurved extensions 53 and 54 of the contact bearing member.

,It will ,thus be seen that as member 27 is moved on its pivots, memberv36 will be snapped from one position to another. As this member issnapped, the jaws at arms 40 of this member will engage the contactbearing member at extensions 53 and 54 and cause said member to besnapped from one position to another. It is evident that by means of thelost motion connection, the dead centers or neutral axes of the twosnapping systems are suiiiciently separated from each other with respectto the motion of the system as a whole as to remove the possibility ofchattering of the contacts.

In order to control the temperature range between which the switch willoperate, an adjustable spring load may be imposed upon the syl- Cap 20covering the free end of 'the bellows is provided with `a cylindricaleX- tension 81, upon which is disposed a coil spring 82. The other endof said coil spring engages a .U-shaped` bearing block 83 adjustablymounted within the housing. This mounting is accom-4 plished by havingarms 84 for the bearing blocl: slotted at 85, Guide pins 86 rigidlymounted 'in walls 5 and 6 of the housing are adapted to said rod may beturned to force bearing block 83 forward or backward and adjust thecompression housing, a sylphon bellows supported in said housing, amember mounted on said housing, means operatively associatingthe freeend of said sylphon bellows with said member whereby said member'hasonly two positions of stable equilibrium and intermediate positions ofunstable equilibrium, said means adapted to transmit movements of saidbellows to said member, an additional member mounted in said housing sothat it has two positions of stable equilibrium with intermediatepositions of unstable equilibrium, electric contacts adapted to be4opened and closed associated with said second member, and a lost motionconnection between said rst and second members for transmitting motionfrom said rst to said second member.

2. An electric switch comprising a housing, a sylphon bellows having oneend thereof rigidly mounted in said husing, a member pivotally mountedto said housing and to the free end of said bellows whereby its free endmay travel in response to movements of said bellows, an additionalmember pivotally mounted in said housing and having a resilientconnectionwith said first member whereby said additional member has twopositions of stable equilibrium and interme- Y diate positions ofunstable equilibrium, a switching member adapted to open and closecontacts and pivotally mounted in said housing so that it has twopositions of stable equilibrium and intermediate positions of unstableequilibrium, and a lost motion connection between said twolastnamedrmembers having stable positions of equilibrium whereby motionsof said bellows operate the said contact bearing member.

3. An electric switch comprising a housing, a sylphon bellows having oneend thereof rigidly mounted in said housing, a U-shaped member havingits free ends pivotally mounted on said housing on each side of saidbellows, means operatively associating intermediate points of the 'armsof said U-shaped member with the free end of said bellows whereby saidmember may swing back and forth on its pivot with movements of saidbellows, another U-shaped member pivotally mounted within said housingand having a spring connection with said first U-shaped member wherebysaid second U-shaped member has two positions of stable equilibrium andintermediate positions of unstable equilibrium, a contact bearing memberadapted to openand close an electric circuit mounted in the housing sothat it has two positions of stable equilibrium and intermediatepositions of unstable equilibrium, and a lost motion connection betweenthe two lastnamed members having stable positions of equilibrium.

4. An electric switch comprising a housing, a

sylphon bellows having one end thereof rigidly j' mounted therein andhaving its free end adapted to move in response to temperaturevariation, a U-shaped member having its free .ends pivotally mounted oneach side of said bellows to irc said housing, means associating thefree end of 13@ said bellowswith intermediate portions of said U'shapedmember. whereby movements of said bellows -will swing said member onsaid pivots, a pair of pivots mounted above saidlbellows on saidhousing, two members mounted onsaid pivots, means associating one ofsaid members'with said housing and the other of said members with saidU-shaped member whereby both of said pivotally mounted members have twopositions of stable equilibrium and .intermediate positions of unstable.equilibrium, electric contacts adapted to be opened and closed by one ofsaid two members and alost motion connection between said two members,having the stable positions of equilibrium.

5. Anelectric switch comprising a housing, a sylphon bellows having oneend thereof rigidly mounted therein and having its'other end free tomove, a U-shaped member having its free ends extending downwardlyandpivotally mounted on each side of said bellows to said housing, meansconnecting intermediate vportions of said U- shaped member with thefreeend of said bellows whereby movements of said bellows result inmovements of said member upon its pivots, .adjustable spring meansacting on said connecting .1 means for governingA the motion of saidbellows,

above said first-named pair of pivots, said' U' shaped member havingelongated slots through which `said additional pivots project andpermitting said U-shaped member to swing about its pivots, a contactbearing member mounted on said fadditionalpivots having two positions ofstable equilibrium with intermediate positions of unstable equilibrium,a second member mounted on said additional pivots having a spring-connection 'with said U-shaped member whereby said second' member hastwo positions of stable equilibrium and intermediate positions ofunstable equilibrium, and a lost motion connection between'said secondmember and said contact bearing'member.

6. An electric, switch comprising'a housing, a

sylphon bellows rigidly mounted within said housing at. one wallthereof, a lever pivotally -mounted adjacent the free end of saidbellows,

a cap pivotally mounted in said lever and adapted to nt over the freeend of said bellows vwhereby as said bellows contracts and expands thefree end of said lever is moved in amplified ratio, and snap-actingswitch mechanism adapted to be operated by the movements'of said lever.

7. An electric switch comprising a housing, a sylphon bellows having oneend rigidly mounted ina wall .of said housing and having its free endwithin saidV housing, a lever pivotally mounted .on said housingadjacent thefree end of said bellows, a cap pivotally mounted -in saidlever and adapted to iit over the free end of said bellows whereby assaid bellows expands and contracts said lever is o scillated, aspringdisposed within said housing, one end of said spring abutting on saidcap, means for adjustably supporting the other end of said spring onsaid housing to vary the spring load bn said bellows, and snap-actingswitch mechanism mounted on said housing and operated by the free end ofsaid lever. ,I

8;" An electric switch comprising a housing, a sylphon bellows mountedwithin said housing at one wall thereof, a lever'pivotally mounted insaid housing adjacent the free end of said bellows, pivotally mountedmeans connecting said free end of said bellows with said lever wherebymovements of said bellows are transmitted to said lever, a coiled springhaving one end thereof' bearing on said pivotally 'mounted means, anadjustable support within said hous-` ing for the other end of saidspring to vary the spring load on said bellows, a pair of pivots in saidhousing mounted above said bellows, two members mountedon said pivots,one of said members being resiliently connected to the free end of saidvlever whereby as said lever oscillates said member is snapped from onestable position to another, resilient means associated with a secondmember whereby said second member has two positions of stableequilibrium and inter- 4mediate positions of unstable equilibrium, alostmotion connection betweenl said two members, and contacts associatedwith said secondlmember.

'9 An electric"v switch comprising a housing, a

sylphon bellows mounted at one end thereof within said housing at onewall of said housing, snap-acting switch mechanism associated with thefree end of said bellows-'and'actuated thereby, a coiled spring mountedin line with said bellows and constituting a load thereon, a pair-of-pins mounted on opposite sides of said spring in said housing, acarriage having slotted ends adapted toco-operate with said pinsdisposed within said housing andserving as an abutment for one end ofsaid spring, and means for lmoving said carriage axially o f said springto vary the lo'ad on` said bellows.

10.An electric switch comprising a pivotally f mountedleverageinitiating system, spring means for biasing said system in one of twoextreme positions, an additional leverage follower system pivotallymounted and similarly biased in one of two extreme positions, means'forconnecting said two -systems together so that a change in position ofone oi!y said systems will result in 'a corresponding changein the otherof said systems, pressure-responsive means associated with' theinitiating system, electrical switching means associated withthe-follower system, and means for varyingthe spring bias on saidilrstnamed leverage system. l

1l. Switching means comprisingan initiating leverage system pivotallymounted and -being spring-biased in one oftwo stable positions, a-

follower leveragesystem pivotally mounted and being spring-biased in oneof two stable positions, a` lost-motion connection between ssaid' twosystems whereby a .change of state in said initiatingsystem willresultin a change of state in said followersystem, means associated with said'initiating system and adapted to cause said system to change its .stateupon predetermined temperature changes, electrical switching mechanismassociated with said follower system and adapted to have its electrical`13"I ccndition'changed as said system changes its state, and means forvarying one of said stable positions in the follower leverage system." i

12. An electric switch comprising a housing,.

a sylphon bellows disposed in said housing and l having one end thereofmovable with respect to said housing, a pivotally mounted leverage sys'tem operatively associated with the movable end of said bellows, anadjustable spring load on leverage system on said housing, a lost-motionconnection between said rst and said second leverage system, andelectrical contacts associated with ,said second leverage system.

` FRED H. OSBORNE.

lthermo-responsive 130 vsaid bellows, an additional pivotally mounted

